I think any used auto has already depreciated. If 12k is going to get you between 100k and 150k miles, how long will you have it before sinking money into it for repairs? If 20k gets you 50-75k less miles on the same car, that's years of driving before you get to the mileage. If I had 'substantial' savings as you state, I'd get the more expensive car and drive it until it was dead or too costly to keep repairing.